This invention relates to a fuel injection system for internal combustion engines, and more particularly to a system for controlling the fuel injection timing of a fuel injection pump.
Fuel injection pumps in general for internal combustion engines such as diesel engine are provided with means for controlling the fuel injection timing so as to obtain a good combustion condition in the engine cylinders. The fuel injection timing control device was originally intended to operate mainly in dependence on the r.p.m. of the engine. However, the injection timing also influences the engine load or the fuel injection quantity, the engine temperature, the exhaust gas concentration, etc. Therefore, it is desirable to control the injection timing in relation to these factors as well.
Particularly, acceleration of an engine deeply concerns the noise, exhaust gas concentration and output characteristics of the engine. For instance, in accelerating the engine, noise or knocking occurs due to an advancement in the injection timing corresponding to the acceleration, and the Nox concentration in the engine exhaust gas increases due to an increased temperature in the engine cylinders. On the other hand, there is a problem that the engine output drops due to a time lag between the accelerating action and the actual advancement in the injection timing.